SHANGHAI - Rescuers in southwestern China tried on Saturday to reach remote communities rocked by back-to-back earthquakes that killed at least 80 people and damaged tens of thousands of buildings, the official Xinhua news agency said.

Friday's shallow 5.6 magnitude quakes struck an impoverished, mountainous part of the country with poor infrastructure and telecommunications and the death toll could rise as news trickles out of cut-off areas, it said.

Most of the victims were from Yiliang county in Yunnan province, near the epicentre.

Officials in neighbouring Guizhou said two people were injured and the lives of nearly 28,000 people were disrupted in Weining county, on the Yunnan border.

Buildings in China's less developed regions are often built with little regard for construction standards, making them susceptible to earthquakes.

The first one at 11:19 a.m. on Friday and the second one about 45 minutes later at a depth of about 10 km according to the United States (US) Geological Survey.

Earthquakes with an epicentre less than 70 km below the surface are considered shallow and can cause significant damage, even at lower magnitudes.

In 2008, about 87,600 people were killed in the southwestern province of Sichuan when a 7.8 magnitude earthquake hit. Many of the victims died in the rubble of homes and schools built without adequate steel reinforcement.